Conventionally, a brake apparatus has been used which brakes the rotation of a wheel by causing a force by an actuator to act on points of force of a pair of link arms rotatable about fulcrums and causing brake linings supported on points of action of the link arms to slide in contact with brake discs.
JP10-505038A discloses a brake caliper unit in which one end parts of caliper levers are coupled to each other, the other end parts are respectively rotationally mounted on brake pads and an eccentric body transmission device provided on a fulcrum between the both end parts of the caliper lever rotates the caliper levers. The eccentric body transmission device includes an eccentric pin configured to rotate by receiving a force by a braking force generator and rotates the caliper lever about the one end part by the rotation of this eccentric pin.
However, in the caliper brake unit of JP10-505038A, a circumferential tangential force acting on the brake pad from the brake disc during braking in which the brake pad slides in contact with the brake disc acts on the eccentric pin of the eccentric body transmission device. Thus, a large force is necessary to rotate the eccentric pin during braking and it has been difficult to improve machine efficiency.
The present invention aims to improve the machine efficiency of a brake apparatus.
According to one aspect of the present invention, a brake apparatus for braking by sandwiching a brake disc rotating together with a wheel, includes a brake main body supported on a vehicle body or a truck; an actuator provided on the brake main body and configured to advance and retract an output member; a pair of link arms having supporting portions between one and other end parts rotatably supported on the brake main body, the pair of link arms being respectively provided to face both surfaces of the brake discs, the pair of link arms having the one end parts coupled by a coupling rod and configured such that the other end parts respectively support brake linings for giving a frictional force by sliding in contact with the brake discs; a lever rotatably coupled to the output member of the actuator and configured to rotate by advancing and retracting movements of the output member; and a booster unit provided on at least one of the one end parts of the pair of link arms and configured to rotate the link arms with the supporting portions as fulcrums by boosting a force transmitted by the rotation of the lever.